motorbicycle building
TRANSCRIPT
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or
440
H68
ding
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c
used
Whit
Emb
Boo
HON.
C
write
Forn
Tick.
Wo-
in.
inside
at the end. The diameter
of
the
prints
at the
other
two
ends
is
l
y
L
in. and
l-j
3
^-
in.
by
i
in.
long.
If
it
is decided
to
do with-
out
core-boxes
for
these two
patterns,
the
larger
part
will have to be
plain-cored
right through
l
T
3
^in.,
leaving
the recessed
portion
for
the
ball-
race
to be machined
out of
the
casting.
The
diameter
of
the
print
for the
lg-in.
tubes is the
same as
for
the
core-boxes,
but
the
length
is
differ-
ent.
The
core
being
supported
in
the
mould
at
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PATTERNS FOR FRAME
CASTINGS.
25
one end
only,
the
print
must be
longer
on the
pattern
than
the
depth
to
be
cored. Thus the
pvint
for
the
top
head
lug
should
be
l\
in.
long,
//and
that
for the bottom
1|
in.
long.
//
Seat
Lug.
The seat
lug (Fig. 17)
is made
from
/
two
turned
parts;
the rear
part,
to
take
the
f-in.
bolt,
is
cut
out
by
hand,
similar in
shape
to
Fig.
18,
and
glued
and
pegged
on.
Turn
the
centre
part
for
the
down
tube 1
T
5
^
in.
in
diameter
in
the
centre,
tapering
to
1
-^
in.
at
each
end
by
If
in.
long,
the
print
standing
out
i
in. at
each
end
by
l
T
V-in.
in
diameter.
The
front
portion
for
the
top
tube
is
ly\-
in. in
diameter at
the
extreme
Fig.
19.
Lower
Horizontal
Lug.
edge,
tapering
up
at
about
3
degrees
of
taper.
The
core-print
for
this
member is
1
T\
in.
in
diameter
by
If
in.
long.
The
rear
part
is
cored out
f
in.,
as shown
by
the
dotted lines
in
Fig.
18,
and will
require
a
print
of
this
diameter,
standing
out
i
in.
at
each end.
Lower
Horizontal
Lugs.
The
patterns
for the
two
lower
horizontal
lugs
(Fig.
19)
are alike
except
in
the
angle,
the one
shown
being
69
de-
grees
and
the
other
57
degrees. They
are
made
from
two
turned
parts,
and
each member
is
to
take
lg-in.
tube.
The
parts
are
exactly
as
the
main
parts
of the
seat
lug,
the
only
difference
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26
MOTOR
BICYCLE
BUILDING.
being
the
absence
of
the rear
ears
and
the
different
angle
of
the front
lug
that
is,
57
degrees.
The
same
remarks
apply
with
regard
to
the core-
prints.
Girder Tube
Lugs. Figs.
20 and 21
are
side
and
top
views
of one of
the
girder
tube
lugs.
A
pair
of
these
will
be
required,
but the
difference
is
so
slight
that one
pattern may
be used
for
both.
This
pattern
should
be
made
with
the
grain
of
the wood
running
with
the
length
of the
pattern,
and the
prints glued
and
pegged
on
each side.
The
drawings give
all
dimensions,
which are
Figs.
20 and 21.
Girder
Tube
Lujrs.
finished
sizes of the
machined
casting,
so
due
allowance
must
be
made for
machining.
The
core
and
print
for
the oval
part
should
be made as
near the finished size as
possible,
as
this
has to
be
filed out in
the
casting.
It
will
be
necessary
to
have
a core-box for the
oval
part
;
a
piece
of
fork
tube
of this size and section
will
answer
ad-
mirably.
The
length
of
prints
for
both
oval
and
round
holes need be
only
J
in. from each
side
of
the
pattern.
Front Fork
Crown.
The
pattern
for
the
front
fork crown is
shown
in
top
and
front view
by
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PATTERNS
FOR
FRAME
CASTINGS.
27
Figs.
22
and 23. It
may
be made
from
one
piece,
with
the
prints
for the
central
core and
two oval
cores
glued
and
pegged
on.
It is
4f
in.
over
all,
If
in.
deep
at the
ends,
where the
forks
fit,
and
1^
in.
deep
in
the centre.
The
central
core-print
is l
T
Vin.
in
diameter,
and
the
ovals,
indicated
by
dotted
lines
in
Fig.
22,
Ij
in.
by
i
in.
;
that
is
the
full
finished
size,
and
owing
to
the awkward-
ness
of
cleaning
out
these
in
the
casting,
it
will
be
advisable
to
core them out
full
size,
or
very
Figs.
22 and
23. Front
Fork
Crown.
nearly
full size.
A
core-box
will
be
necessary
for
this
pattern,
allowing
for
a
uniform
thickness
of
-
in. in the
casting,
as shown
by
the
dotted
lines
in
Fig.
23, except
at
the
edges
of the
oval
open-
ings,
which
may
be a
bare
/
a
-
in. It
will be
noticed that
a
ring
or
collar
is
shown
on
top
of
the crown
;
this
is
for the
bottom ball-race
to
fit
on.
The
core-prints
need
only project
f
in.,
as
the
core
will
be
supported
at
four
points.
Ball-head
or
Steering
Tube
Lug.
The
ball-
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28
MOTOR
BICYCLE
BUILDING.
head,
or
steering
tube
lug,
is
shown
by
Figs.
24
and
25,
these
being
side
and
bottom views.
It is
made
by
turning
the
main
part
to
the
dimensions
given,
allowing
for
machining.
The central core-
print
is
ly^in.,
projecting f
in. at each
end. The
rear
part
for
the
f-in.
bolt
is cut
out
separately,
and
glued
and
pegged
on.
It
is l
in.
wide,
and
has a
f-in.
core-print.
The
two
projections
to
Fig.
25.
Figs.
21
and
2o.
Steering
Tube
Lug.
receive
the
ends of
the
girder
tubes are cut out
to
shape
as
in
Fig. 25,
length
with
the
grain,
and
the two
lugs
turned
to
shape
and
glued
and
pegged
on.
The
prints
are
y
7
^
in.
in
diameter
by
f
in.
long.
The
two
projecting
pieces
being
so
light
(only
T
3
(T
in.
thick),
they
should
be dovetailed
into
the main
part
of
the
pattern,
as well as
glued
and
pegged,
or
they
may
soon
be broken off
at
the
foundry.
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PATTERNS
FOR FRAME CASTINGS.
Engine
Plates.
The
pattern
for
the
engine
plates
is shown
by
Figs.
26
and
27,
which
are
side
and
end
views. Four of
these
plates
will
be
re-
quired.
They
may
be cast in malleable
iron
from
a
pattern,
but
it
is better
to
have
them
forged
from mild steel.
Should
castings,
however,
ba
used,
have
only
the
large
centre
hole
cored,
leav-
ing
the
ends
solid
to be
drilled
out in
the
casting.
Fig.
20.
Fig.
27.
Figs.
26
and
27.
Engine
Plate.
This
also
applies'
if
forgings
are
used,
as
the
exact
position
of.
these holes
can
only
be
ascer-
tained
when
the
frame
is
built
and
the
engine
tried
in
the
frame,
with
wheels in
position.
Leave
on
Patterns.
This
is
all
the
pattern-
making
that
will
be
necessary,
and
it
only
re-
mains to
get
the
required
number
of
castings
made
from
them
at a
good
malleable iron
foundry.
All
parts
of the
patterns
must
be
nicely
smoothed off
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30
MOTOK BICYCLE BUILDING.
with
fine
glasspaper,
leaving
no
rough
edges
or
parts,
and
care
must
be
observed
to
impart
suffi-
cient
leave
to
the
various
parts
requiring
it.
What
is
meant
by
leave
on
a
pattern
will
be
understood
by
taking,
first,
a solid ball
and
then
a solid
square
as
patterns.
The ball would
be
moulded half
in
each
moulding
box,
the
parting
taking place
exactly
at the centre of the
pattern
;
thus,
as all
parts
of
this
pattern slope
away
from
the
centre
or
parting
line,
no
leave
would be
necessary,
as this
would
be
a
perfect
form for
leaving
the
sand
well.
But
if a solid
square
or
cube is
taken,
some
part
of
the
pattern
would
have to
be
tapered
off
to
enable the
pattern
to
come
away
from the sand
without
breaking
down
some
part
of
the
impression,
unless the
pattern
was
moulded
with
a
corner of the
square
upper-
most,
and the
parting
takes
place
at a
point
which
embraces four corners.
Whatever
other
position
this
pattern
might
be moulded
in,
some
portions
of
the
flat
sides
would
have
to
be
tapered
off from the
parting
line
to enable
it to
leave
properly.
It
is
only
necessary
to
look
at
a
pat-
tern
carefully
and
imagine
which will
be
the most
convenient
position
to mould
it
in,
to
see
what
parts
require
leave.
Painting
Core-prints,
etc.
All
core-prints
should
be
painted
black
a
little
vegetable
black mixed
with
varnish will
do
and
the
whole
pattern
given
two
coats
of
shellac
varnish. This
varnish can be
easily
made
by
dissolving
brown shellac
in
methylated
spirit, shaking
the bottle
frequently.
Heat
will
assist
it
to
dissolve,
but
great
care must be
taken,
as
the
spirit
is
very inflammable,
and
likely
to cause
an
accident
if
taken
too
near a
light.
The
inside
of
the core-boxes
should
also
be
given
two
good
coats
of shellac
varnish
when
finished.
Making
Plain
Round
Cores.
For
making
the
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PATTEKNS FOR FRAME
CASTINGS.
31
plain
round
cores,
nothing
beats
cycle
tube,
and
pieces
of
this
to
fit
the
various
prints
should be
selected
and
cut
to
the
required
lengths.
Where
the
junction
of two
cores
is
at an
angle,
such
as
the head
lugs,
seat
lug,
and lower horizontal
tube
lugs,
the core tubes
should
be
cut
off at a cor-
responding
angle,
and also
hollowed out at the
angle
end,
so
that
the
coring
may
extend as
far
as
possible.
Oval Gores.
For
the
oval cores
also
pieces
of
fork
blade
of the
proper
section
will
do
perfectly
for
making
the
cores,
and
will
save
a
deal
of
trouble
in
core-box
making.
Dowelling
Halves
of
Gore-boxes. The
two
halves
of
the
core-boxes
for
fork
crowns,
or what-
ever core-boxes
that are
made
in halves,
should
be fitted with two
or
three
dowels
to
ensure
the
halves
closing perfectly
accurate
;
they
should fit
easily,
but
without shake.
Small brass
pegs
and
sockets can be
purchased
for
the
purpose,
and
where
the boxes
are
likely
to be
used much it
is
advisable
to fit
these,
as
the wood
dowels soon
wear
with
much
usage.
Metal
Patterns.
Where
a
large
number of
castings
are
to
be
made
from
one
pattern,
metal
patterns,
preferably brass,
are
made,
and
cast-
iron
core-boxes used.
Dimensions
on
Illustrations.
It
must
be
borne
in
mind that
all dimensions
given
in
the
illustra-
tions
included
in
this
chapter
are
finished
sizes
of
castings,
and
due
allowance
must be
made
for
machining.
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CHAPTER
III.
BUILDING FRAME
FROM
CASTINGS.
HAVING
received
the
castings
from
the
foundry,
free them
well
from
sand
;
and should
any
castings
have
become
distorted in
the
annealing
process,
correct
this
by
careful
hammering.
Bottom Bracket. The bottom
bracket
may
first be
taken in
hand. Chuck
the
casting
in
a
jaw
chuck,
and bore
out
the
centre
part
ly
7
^
in. in
diameter, leaving
f
in.
at
each
end
a
full
\^
in.
to
screw
if
in.
by
24
threads.
Face off
the end
standing
out from
the
chuck
at
this
setting
;
the
other end
should
be
faced
off on a
screwed mandrel
to
get
perfect
truth
;
but
if
carefully
chucked,
it
may
be
faced
fairly
true
by
this
means.
The
bracket
cups
should
be
obtained
or
made
previous
to
screwing
the
bracket,
so
that
they
may
be
tried
in
to
fit
before
removing
the
casting
from
the
chuck.
The
cups
should be a
good
tight
fit,
so
that
they
can
only
just
be
screwed
up
with
a
peg
wrench. The width of
the
bracket when
finished
should
be
3^
in.
Boring
the
Three Tube
Lugs.
The best
way
to
bore the three
tube
lugs
will
be
on
an
angle
plate
or an
upright
drilling
machine
;
but if
such
a tool
is
not
available,
the
lathe
will
do,
either
by
bolt-
ing
the
angle
plate
to the
face
plate,
or
by
hold-
ing
the
casting
in the
jaw
chuck.
If
the
latter
method
is
adopted, greater
care
will
be
necessary
in
seeing
that
the
holes
are
bored
at
perfect
right
angles
to
the
centre bore. With
a
true
angle
plate
and
the
ends
of
the
casting
faced
true,
this
will
be
ensured.
The
front
member,
to take
the
tube
from
the
back
fork
crown,
will be
bored
If
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BUILDING FRAME FROM
CARTINGS.
33
in.
right through
into
the
centre,
and the
outside
trued
up.
The
lug
to
take
the down
tube
will now
be
bored
Ij
in.
right
through,
and
at
an
angle
of
110
degrees
with
the
first
boring.
The
rear
lug
is
bored
If
in. at
an
angle
of
64
degrees
with
the
last
boring.
The various
tubes
should
be
tried
in
their
places
before
the
casting
is
shifted,
and
should be a
good tight
push
fit in
their
holes.
Holes
for
lubricators
should
be
drilled
f
in.
from
each
face,
in
such
a
position
that the
lubricators
will
be
upright
when
the bracket
is
in
position.
If
lugs
for
set
pins,
by
which
the
cups
or
discs
are
to be
locked,
have
been
provided,
these
should
be
drilled and
tapped
to
suit
the set
pins.
The
dimensions
of
the
disc to be used with
lock-nuts,
and
also
of
the
bracket
axle,
will
be
given
later.
Back Fork
Crown.
The back
fork
crown
cast-
ing
should
be
chucked
in
the
jaw
chuck and
bored
If
in.,
as
deep
as
possible,
and the
edges
trued
up
;
or
the
ends of the D-section
projections
may
be
levelled
off
and
the
casting stripped
to
the
face
plate
to bore this
If
in. hole.
Whichever
method
is
adopted,
care
must
be
taken
to
get
the
hole
perfectly
true
with
the
D
ends.
Engine Lugs.
The
engine lugs
should
be
chucked
true,
and
the
f-in.
holes bored
right
through
and
reamered,
the faces
being
turned
up
on
a mandrel.
They
should
measure
3^
in.
over
all when
finished.
The
tube
lugs
should
then be
bored
ij
in. and
If
in.
respectively,
and
the
edges
trued
up.
Front
Fork
Ends. The
castings
of
the
front
fork
ends
will
require very
little
machining.
The
f-iri.
hole
will
require
drilling,
and
the
f-in.
recess
should
be
machined
in
the
outside face of
each
with
a
peg
drill
or
cutter.
The
slot
can
then be
filed
out to
meet
the
f-in.
hole.
The
f-in.
lug
to
take
the
bottom
end
of
the
girder
tube
can
be
turned
or
filed as
preferred.
As
this
is a rather
awkward
casting
to
chuck,
it
may
be advisable
to
c
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3i
MOTOR BICYCLE
BUILDING.
file
this
to
fit
the
tube at
the
same time
as
the
oval
lug
is
filed to fit
the
lower
end
of
the
oval
fork blade.
Whilst
these
are
being
fitted
to their
respective tubes, they
should be
tried
on
the
full-
size
drawing
to
see
that
the
angle
is correct. The
two
stay
eyes
will
require
drilling
out
f
in.
;
these
may
be
drilled
at
the
same
time
as
any
of the
other
|-in.
holes.
Head
Lugs.
Chuck
the head
-lugs
in
the
jaw
chuck, large
end outwards
;
bore
through
Ij
in.
to
fit
the
head
tube,
and
turn
out
the
recess
fo,r
ball-races,
as
shown
by
the dotted
lines
in
Figs.
15
and 16
(p. 23).
These
recesses
will
measure
^\
in.
at
the extreme
ends
by
^
in.
deep.
Face
off the
ends,
and true
up
the
outer
edges.
The
Ij-in.
tube
members
may
be bored
whilst
held
in
the
jaw
chuck
or
on
the
angle plate,
tilted
to
the
correct
angle
112
degrees
for
the
top
head
lug
and 56
degrees
for
the
bottom one.
Seat
Lug.
Chuck
the
seat-lug casting
in the
jaw
chuck
to bore
out the
central
lj-in.
hole,
with
the
top
end outwards
;
re-chuck
or fix
on
the
angle
plate,
to
bore
out the
Ij-in.
hole
for
the
front
tube.
The
rear
part
will have
to
be
drilled out
|
in.,
and
ths
ears
faced
off
true
for the
back-stay
eyes
to
bed
against.
The
saw-cut should
be
put
in
the
back,
midway
between
the
ears,
before
the
lug
is
fitted
and
brazed to
the
seat
tube,
as
the
casting
becomes
very
hard
and
difficult
to
saw
after it
has
been
brazed.
Lower
Horizontal Tube
Lugs.
The treatment
of
the
lower
horizontal
tube
lugs
is
the
same
as
that of
the
seat
lug
;
but
note
should
be
taken
of
the
difference
in the
angle.
Drilling
Girder Tube
Stays.
The
|-in.
hole
in
each of
the
girder
tube
stays
may
be
bored
on
the
drilling
machine or
the lathe. In
setting
these
castings
for
boring
the
|-in.
hole,
due
allowance
should
be
made
for
the
difference in
parallel
be-
tween this
and
the
oval
hole. On
reference
to
the
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8/10/2019 Motorbicycle building
37/166
BUILDING
FRAME
FROM CASTINGS
35
full-size
drawing,
it will
be
noticed that
the
girder
tubes
approach
nearer
to
the
centre
steering
line
as
they
reach the
top
of the
head.
Also,
looking
from
the
front
of
the
machine,
it will be seen
that
the two
tubes
are closer
together
at
the
top
than
they
are
at
the fork crown.
If
this difference
is
allowed
for
when
drilling
the
f-in.
holes,
it will
not
be
necessary
to
bend the
tubes
to
bring
them
into
place.
Knocking
these
lugs
on
a
f-in.
man-
drel,
after
they
are
drilled
and the
edges
trued
up
in
the
lathe,
will
add
greatly
to
their
appearance.
The
oval holes must be filed out
to
fit
the fork
blades.
Front Fork
Crown.
The front fork crown
may
be
held
in
the
jaw
chuck or
strapped
to
the
face-
plate,
the
centre
hole
bored
1|- in.,
and
the
top
faced
off
and
the
shoulder turned
1^
in.
in
diameter
by
|
in.
deep.
If
the
casting
is
being
machined, strapped
to the
face-plate,
this latter
operation
will have- to be done on a
mandrel be-
tween the
centres.
The
oval-section
holes
will
have
to
be
filed
or
scraped
out
for
the
fork
blades
to fit.
While
the
casting
is
on
the mandrel in
the
lathe,
the
ends
of
the
ovals
may
be
faced
off
true.
Steering-tube
Lug Casting.
Chuck the steer-
ing-tube
lug casting
bottom or
large
end
outwards,
bore
through
lj
in. to
fit
the
steering
tube
(a
tight
hand
fit),
and
recess out
the
part
shown
dotted
in
Figs.
24
and
25
(p.
28)
to
take
the
ball-race.
This will
be of
the
same
size
across
as
the
recesses
in
the
head
lugs,
but
V
in.
deeper,
so
that
the
edge
of
the-
casting
may
overlap
the
outer
edge
of
the
top
ball
head
lug
when the two are
brought
together
with
the
balls
in
place.
This
hides
the
balls,
and
keeps
the
bearing
more
or
less
dust-
proof.
The
bottom
ball
head
lug
should
be
made
to
overlap
the
bottom
ball-race
on
the
fork
crown
in
the
same
manner
for
the same
purpose.
At
this
chucking,
the
under side of
the front
ears
may
be
faced,
as
well
as the
edges
of
the
two
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8/10/2019 Motorbicycle building
38/166
36
MOTOR
BICYCLE
BUILDING.
girder
tube
lugs,
on
a
mandrel
in
the
lathe
centres
;
the
outside
and
top
of
the
casting
may
be
turned
up,
or as much
of
the
outside
as the
projections
will
allow.
The
ears
should
be drilled
out
|
in.,
and faced
on both
sides
with
a
facing
cutter
;
the cutter
that
was
used
for
recessing
the
front
fork
ends
will
do
for
this
also.
The
two
^-in.
holes
for the
girder
tubes
must now
be
drilled,
and
finished
out
with
a bottoming
drill
or
cutter,
so
that
the holes
have
square
corners or
a
flat
bottom.
A
fine
saw-cut
should be
made
nearly
half
through
the
casting, just
under
the
ears,
as shown
in
Fig.
24
(p.
28),
and a
broader
cut
should
be
run down to
meet this
midway
be-
tween
the ears.
Engine
Plates.
The
four
engine-plate castings
should
be
levelled,
the
|-in.
holes
drilled
square
with
the
face,
the sides
smoothed,
and the
edges
filed
up.
One
of the
|-in.
holes in
each
plate may
be
marked
off
and
drilled,
leaving
the other
|-in.
holes
to
be
marked
off and
drilled
after the
frame
is
built
up
and
the
engine
is in
position.
Ball-races.
It
will now
be
necessary
to
make
the
ball-races
(Figs.
28 and
29,
p.
37).
Four of
these will
be
required three,
as
illustrated,
for the
steering
tube
lug
and the
top
and bottom head
lugs,
and
one
for
the fork crown
;
this
last
will
have
square
corners instead
of
round,
and
a
lyV
in.
hole
to
fit
the
shoulder
on
the
fork
crown,
the
outside diameter
being
1^4
in.
These
are
rather
awkward
to
make
in
an
ordinary
lathe
;
to
get
them true
they
are
made
on a
large
hollow
mandrel
lathe
from the bar.
It would
be
as
well
to
buy
these
ready-made,
as
they
do
not
cost much. If
it
is
decided
to
make
them,
good
mild
steel,
well
case-hardened,
should
be
used.
It
would
be
simpler,
in
making
the
steering bearings,
to
dis-
pense
with
cups
or loose
ball-races
altogether,
and
turn
the
ball-races
in the head and
steering
lugs
themselves,
with a steel
cone
only
to
fit on
the
fork
-
8/10/2019 Motorbicycle building
39/166
BUILDING
FKAME FROM
CASTINGS. sf
crown.
In
this
case
the
bearings
should
be
two-
point
bearings,
and
not
four-point,
as
shown
with
the
loose
ball-races.
These
parts
will not
bo
so
durable
as
well-hardened
steel ball-races
;
but
if
balls
not
less
than
^'V
in.,
or
T
3
(I
in. for
the
top
bear-
ing
and
-^L
in.
for
the
bottom
bearing,
are
used,
they
will
wear
very
well.
The malleable-iron
castings
become
very
hard when
they
are
brazed,
and
thus
stand a
lot
of
wear.
The
loose
steel
cone on the head
will,
of
course,
be
well
hardened,
and
the
radius of
the
bearing
curves
should not
be much
greater
than the radius
of
the
ball
used,
thus
giving
a
good large
bearing
surface,
instead
of
the
small
bearing
surface
usual with
V-groove
Fig.
28.
Fig
29.
Figs.
28 and
29.
BalJ-race.
bearing
discs.
One
advantage
of
the
absence of
loose
ball-race
bearings
is
that there
are
no
separ-
ate
parts
to
gst
loose
and
cause
play
in
the
head
Bottom
Bracket
Axle.
Fig.
30
gives the
full
dimensions
for
the
bottom
bracket
axle,
which
should
be
made,
preferably,
from
one
of Lead-
beater
&;
Scott's
patent stampings.
These
have
a dead
soft
centre,
which
will not
harden,
with
an
exterior
covering
of
a
carbon
steel
that
will
harden
direct
in
water,
and
gives
a
very
hard
wearing
surface.
Failing
one
of
these-
stampings,
cast
steel
should be
used,
carefully
hardened at-
the
wearing
parts only.
Mild
steel,
case-hard-
ened,
does
very
well
for
this
job
if
proper
facilities,
are
at
hand
for
pot-hardening
;
but
using
mild
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8/10/2019 Motorbicycle building
40/166
3S
MOTOR BICYCLE BUILDING.
steel,
and
attempting
to harden
by
the
ordinary
means on
the
open
hearth with
potash,
etc.,
is
quite
useless.
In
making
this
axle,
cut off
the
steel
or
stamping just
the
dead
lengths
required
before
drilling up
the
ends,
so that the centres
upon
which
the
axle
is
turned
may
be
left
in,
to true
it
up
by
after
hardening.
Fit
the cranks
and file
the
keyways
before
hardening.
Special
wide bracket
discs
are
used
with
this
axle,
as
shown
at
A,
lock-
nuts
(Figs.
31 and
32)
securing
them.
If it has
been decided to
lock
these
discs
by
set
pins
or
transverse
cotters,
the
ordinary
standard
pattern
discs,
which
can
be
purchased
for about
6d.
each,
will
do.
Should lock-nuts
for
the
bracket
discs
be
Fig.
30.
Bottom Bracket
Axle
in
Position.
necessary,
they
may
be
made
from
ordinary
gas
back-nuts,
bored
out and
re-screwed,
if suitable
stampings
are not
available
; or,
if
the latter are
used,
they
can be made
from
stout 1-in.
washers,
bored and screwed.
They
need not be filed
up
or
shaped hexagon ;
but a
couple
of
deep
notches
may
be
filed in their
edge
for
adjustment pur-
poses,
as
shown
in
Figs.
31
and
32.
They
should
be
If
in.
by
24
threads,
the
same
as
the
discs,
but
must
be
a
somewhat
easier
fit
on
the
discs
than
the
discs
are
in
the
bracket,
otherwise
diffi-
culty
will
be
experienced
in
adjusting
the
bearing
properly.
At
least
one face
of
the
nuts
must be
trued
up
with
the thread.
Fitting
Lock-nut
to
Steering
Tube.
The
steer-
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8/10/2019 Motorbicycle building
41/166
BUILDING FRAME FROM
CASTINGS. 39
ing
tube
must be screwed
at one
end
with a fine
thread for
|
in. down. A
coarser thread
than
26
to
the
inch should
not
be
used,
otherwise
the tube
would
be
weakened
by
the
depth
of
the
thread.
A
lock-nut
to fit
this
will
be
required,
and
the
re-
marks made
with
reference
to
the bracket lock-
nuts
applj
7
also
to this.
Whilst
screwing
the
steer-
ing
tube
and
fitting
the
nut,
pay
attention
to
the
fitting
of
the
steering-tube
lug,
which
must
be
a
good
sliding
fit
without
shake.
The
saw-cut,
which allows
the- tube
to
be
tightened
on
to
the
Fig-.
32.
Figs.
31
and
32.
Bracket Lock-nut,
handle-bar
stem,
should
not
be
made
until
the
handle-bar
has
been
fitted
in
the
tube.
Engine
Bolts. Two
f-in.
turned
engine
bolts
(Fig.
33)
will be
required
for
securing
the
engine
plates
to their
lugs.
These
are turned from
li-in.
mild
steel,
one to the
dimensions
given
in
the
illustration,
and
the
other
\
in.
shorter.
They
should
be
a,
good push
fit,
without
shake,
in the
f-in.
holes
of
the
engine
plates
and
the
lugs
on the
frame.
Building up
Frame.
All
the
lugs
and
parts
having
been machined
ready
for
fitting
up
to
the
various
tubes,
the
rear
part
of
the frame
may
now
be
built
up.
Cut
off
the
back
forks
to
the
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8/10/2019 Motorbicycle building
42/166
40
MOTOR
BICYCLE
BUILDING.
exact
length
required
;
clean out
the ends
where
the fork ends
and
fork crown
ends
fit
;
level
off
the
ends
where
the
fork
ends
fit
;
and
chamfer
off
the
inner
edge
of
the
D
tubes,
so
that
they
fit
neatly
up
to
the
shoulders.
If
these
fit
tight,
they
need not be
pegged
for
brazing.
Fit the
top
stay
eyes,
into the
top
back
stays
in a
similar
way.
Cut
a small
notch
in the bottom
of
the
f-in.
hole
in
one
of
these
stay
eyes,
so
that a
small
peg
fitted
under
the head
of
the
bolt,
which
holds the
seat
pillar
tight,
may
engage
with
this
slot
and
so
prevent
the bolt
from
turning
while the
nut
is
being
tightened
or
undone.
Before
fitting up
the
fork
ends
and
stay
eyes,
or
cutting
the tubes
at
all,
see
that
the cranked
portion
of these
comes
in the
proper
position
to
allow
of
the
belt
rim
clearing
properly,
and
on the
left-hand side of
the
machine.
These four
joints
are
then
brazed
and
filed
up.
Setting
Rear
Fork
Ends.
The
fork
ends
should
now
be set on
the
wheel.
(The
wheels
should
be made
or
procured
before
starting
to
build the
frame.)
To
set the
fork
ends,
tighten
up
in
their
place
on
the
wheel
spindle
and
set
until
the
other
ends of
the
forks
are
the
proper
distance
apart,
to
correspond
with
the
D-section
ends
of
the
fork
crown,
and
at
an
equal
distance
from the
edge
of
the
whe-el rim.
It
is
better not
to
set
these* in their
place
on
the
spindle,
or
the
latter
may
get
bent with the strain
;
they
should
be
removed to the
vice to
be bent
to
the
required
angle.
Brazing
Tubes
to
Bottom
Bracket.
The two
short
pieces
of
If-in.
tube
may
now
be
fitted
to
the
bracket,
and
also
the down
tub,
after
thoroughly
cleaning
out
the
various
lugs
and
the
ends
of
the
tubes.
The
ends
of
the
If-in.
tube
that fit
into
the
bracket
should
be
hollowed
out,
to
allow
of
the
tubes
fitting
well
up
into
the
bracket. The
back
fork
crown is then
fitted
to
the other end
of
the
If-in.
tube.
Now
try
this
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8/10/2019 Motorbicycle building
43/166
BUILDING
FRAME FROM
CASTINGS.
41
part
on
the
working drawing,
and see that all
the
measurements
and
the
angle
of
the down tube
are
correct.
Before
pegging
these
joints
and
braz-
ing up,
make
sure
of
the
following
points
:
The
down tube
must
be
at
right angles
to the
bore
of
the
bracket
;
test
this
with a steel
straightedge
on
the
trued-up
faces.
See that
the
back
fork
crown is
square
with
the
down
tube
;
test
this
by
placing
the-
straightedge
on
the
top
of the
D-sec-
tion ears
and
sighting
it from
the
back,
when
the
straightedge
should
appear
at
right
angles
to
the
down
tube. Some
blacklead mixed
with
oil
should
be
rubbed
into
the threaded
ends
of
the
bracket,
and
also
into
the
tapped
lubricator
holes,
to
pre-
vent
the brass
and borax
adhering
to
these
parts.
Fig.
33.
Engine
Plate Bolt.
These four
joints
will
require
careful
brazing,
and
a
good
blast
to
obtain sufficient
heat. The best
way
to
proceed
is to direct
the
blast on
to
the
heavy portion
of the front
lug
;
get
this
well
heated
up,
and
make
the
front
l|-in.
joint.
Now
shift
the
flame
on
to
the
root
of
the
l^-in.
lug,
and
braze
this
joint
;
then
on to
the
heavy
part
of the
rear
l|-in. lug,
and finish
this
joint.
It
will
be advisable
next to remove the
job
from
the hearth
and
thoroughly
brush
these
joints,
while
well
hot,
with
the
wire
brazing
brush.
The
joint
of
the
rear
If-in.
tube with the
back fork
crown
can then
be
finally
brazed.
Brazing
this
last
joint
will
scale
the
D
ends of
the
crown,
and
these
must therefore be
cleaned
up
again
before
fitting
the
back forks. Small air-holes
must
be
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8/10/2019 Motorbicycle building
44/166
42
MOTOR
BICYCLE BUILDING
drilled on
the
inside of
these
back
forks
before
filing
up
and
brazing.
Other tubes
requiring
air-
holes
for
brazing
will
be
the back
stays,
lower
horizontal
tube,
and
front
forks
;
and
the
top
tube
and
bottom,
front
tube
as
well,
unless
the
ends
of
these
are
opened
out
into their
lugs.
When the
back
forks,
exactly
equal
in
length,
are
finally
fitted
to
the
crown,
remove
and
load
each tube
with brass
and
borax,
knock
the
joints
well
home,
and
peg
securely.
Fix
a
stay
or
strut
between
the
two
fork
ends,
so that
they
will
be
held
the
same distance
apart
as
they
will
be
when the
wheel
is in
position.
In
the
absence of
a
suitable
stay,
the hub
spindle
will
do,
the
cones and
nuts
being
used to
keep
the
fork ends
the
correct
dis-
tance
apart
and
the
faces
square with
each
other.
Shake
the
charge, placed
inside
the
tubes,
well
down
towards
the
joints,
and
braze
one
at
a
time,
with
the fork on its
side.
Fitting
Ball-head.
Fit
up
the
ball-head
tube
to
the
top
and
bottom
head
lugs,
the
top
tube
to the
top
head
lug,
and
the
bottom
front tube
to
the
bottom
head
lug,
and
peg
the
joints.
The
ends
of the tubes
should
be hollowed out to fit
up
against
the
head
tube.
Before
brazing,
see that
the
three
tubes are in
one
plane
;
to
test
this,
place
a
long
straightedge
across
the ends
of
the
top
and bottom
tubes,
and
sight
this with
the
ball-
head
tube.
Also
see
that
the ends
of
the
tubes
are
the
proper
distance
apart
to
drop
into
place
with
the seat
lug
and
front
engine
lug
on
the
draw-
ing.
While
these
joints
are
hot,
scrape
out
the
ends
of the ball-head
lugs,
where
the
ball
races
fit
;
this
will save a
lot
of
work
after,
if
any
brass
has stuck to these
parts.
Mark
off,
on
the
down
and
bottom
tubes,
the position
that
the
Ipwer
horizontal
tube
lugs
will
occupy,
and
clean
the
tubes
at
these
parts.
Slip
the
two
lugs
on
to
the
down
and bottom tubes
before
the
seat
lug
or
the
front
engine
lug
is
fitted
to
its tube.
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BUILDING
FRAME FROM
CASTINGS.
43
Fitting
Front to Rear
Parts.
The seat
lug
can
now
be
fitted to
the
top
tube,
and the
lower
horizontal
tube
to
its
lugs,
and
the
front
and
rear
portions
of the
frame connected
together
by fitting
the
seat
lug
on
to
the
top
of the
down
tube.
In
fitting
this
front
portion
to
the
rear
part,
see
that all
the
tubes
lie
in one
plane
before
pegging
up.
To test
this,
place
a
long
straightedge
across
each
side
of
the ball-head
and down
tubes
;
the end
of
this should
fall
at
an
equal
distance
from each
fork-end face.
The
ball-head
tube
must also
be
perfectly parallel
with
the
down tube.
These
three
joints
may
now
be brazed
up.
The
top
tube
is
opened
out into the seat
lug
by punch-
ing
a
hole
through
the down
tube
inside the
seat
lug.
This
will
act
as
an
air
hole,
and
serve
as
a
means
of
feeding
a
charge
of brass and
borax
to
the
joint.
The
lower horizontal
tube
lug
joints
may
be
fed
by ramming
a
piece
of
paper
down the
tube,
about
the
centre,
before
fitting
up
;
a
charge
can then be
inserted
at
each end
of the
tube,
the
paper
keeping
them
apart.
Fitting
Top
Back Stays.
The
top
back
stays
may
now
be
fitted
and brazed
up.
Before
pegging
up
these
two
joints,
the
wheel
must
be
tried
in
place,
and
the
stays
so
fitted
that
the
rim of the
wheel
is
exactly
central between
them.
Fit
the
mud-guard
stay,
and braze in
place,
to
give
1^-in.
clearance between
the
mudguard
and the
tyre.
The
fitting
and
brazing
of the
engine
lugs
had
better
be
left
until
the
front forks
are built
and
the
engine
is
ready.
Fitting
Front
Forks.
Now
the front
forks
may
be
secured.
Fit and
braze the
steering
tube
to
the
fork crown
;
then
square
off
the
bottom ends
of
the
front
forks
and
clean
out
all
scale,
and
serve
the
lower ends
of
the
girder
tubes in the
same
way.
Fit
the
fork
ends to the
fork
blades,
set
in
the same manner as the rear
fork
ends
on
the front
wheel,
and braze
up
these two
joints.
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44
MOTOR
BICYCLE
BUILDING.
Next
cut
off the
top
ends
of the
blades to
the
proper
length,
to
give
the
required
clearance to
the
tyre
under
the
fork
crown.
Clean
the
ends
of
the
blades
outside
sufficiently
far
down
to
allow
for the
girder
tube
stays,
then
slip
these
stays
on
over the
fork
blades,
load each
with
brass
and
borax,
and fit
into the
crown,
taking
care to
knock
them
well
home.
The
two blades
should be
of
exactly
the same
length,
and,
after
being
tested,
should
be
fixed
at
an
equal
angle
to
the
steering
tube when the ends
are
the
proper
distance
apart.
Fit the
wheel
in
the
forks,
and
see
that
the
rim
is
central
between
them,
and use
the
straightedge
to see
that
the
steering
tube is
true
with
the wheel
rim.
When
this is
all
as-
sured,
fix
the
wheel
spindle
or other stay
between
the fork
ends,
and
peg
and
braze
up
the
four
joints.
The
f-in.
holes
of the
girder
tube
stays
must
now
be cleaned
out,
the tubes where
they
fit
these,
and
the
inside
of
the
lower
ends,
to fit
on
the
front
lug
of
the
fork
ends.
The exact
length
of
these
two
girder
tubes
is
obtained
by
assembling
the
ball-head
with
balls
and
races
in
position.
It is
very important
that the
length
of
these
shall be
absolutely exact,
for
if
they
are
the
least
bit
too
long,
the ends would bottom
in
the holes
of
the
lugs
on
front
of
the
steering-tube
lug
before the
bearing
was
properly
adjusted.
The
tubes should
be
of
such
a
length
as
to
be
about
~
in.
off
the
bottom
of
the
holes,
when the
bearing
is
tightly
adjusted.
This
allows
for
subsequent
wear
and
adjustment
of
the head
bearings.
Of
course,
it-
is
understood that
the
tops
of
these
tubes are not
brazed
into
the
lugs,
but
are
a
good
tight sliding
fit
in
them.
When
the
proper
length
has been
obtained,
take
down
the
head and
braze the
four
joints
at
the crown
and
lower
ends.
It will
be as well
to
slip
the
steering
tube
lug
on
to
the
top
ends of
the
girder
tubes
while these
four
joints
are
being
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BUILDING
FRAME
FROM CASTINGS.
45
brazed,
thus
ensuring
them
being
the exact
dis-
tance
apart
to
drop
afterwards
into their
places.
Before
filing
up
the
fork
joints*
try
the
front
wheel
again,
to see
if
any
part
has
sprung
or
given,
and
thus thrown
the
wheel
out
of
centre.
It
will,
of
course,
be
better
to correct this
now
than
to
wait
until after
the
joints
are
filed
up.
While
the wheel
is
in
the
fork,
both before and
after
brazing,
place
the
straightedge
across
the
front
of
the
fork
crown,
and
see
that
is is
parallel
with
the
wheel
spindle.
Should
the fork
be
on
the
twist,
this
can be rectified
by
holding
the
crown
in the vice and
inserting
a bar between
the
lower
end
of
the
fork
blades.
Handle-bar and
Seat
Pillar.
The
handle-bar
and seat
pillar
call
for no
special
mention,
ex-
cept
that
they
are
stronger
than
the
ordinary
cycle
type,
and that
the
handle-bar
is
wider and
longer,
as
already
mentioned. The
stem
of both
the
seat
pillar
and the handle-bar
should
be fitted
into
their
respective
tubes before the saw-cut is
made
down
them.
Fitting
Engine
Plates.
If
the
engine,
or
the
crank
case
of
the
engine,
is
now
available,
the
four
engine
plates
can
be fitted to
the crank case.
The
pair
on
the
pulley
side will
be
let
in
flush
with
the surface of
the crank
case,
so
as to
give
clearance to
the belt.
With the
engine
lugs
slipped
on
to
the
ends
of
the
bottom
down
tube
and
the
short
l--in.
tube,
the
proper
position
for
the
f-in.
holes
in the
engine
plates
and
the correct
position
of
the
engine
lugs
on
the
tubes
can
be
marked
off
to
bring
the
engine
square
and
per-
pendicular
in
the
frame.
The
two
lugs
should
be
pegged
on
the
tubes
while
the crank
case
and
plates
are
in
position
with
alj
bolts
in,
to ensure
their
coming
together
again
properly
when
brazed
up.
It
will
be
advisable to
blacklead
the inside
of
the
f-in.
holes
in
the
engine
lugs
before
brazing
to
prevent
them
scaling
or
getting
brass
on
them.
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47
CHAPTER
IV.
MAKING
A
3i-H.P.
PETROL
MOTOR.
THE motor
to
be
described
in
this
chapter
will
develop
3i
h.p.,
and is suitable
for
the
frame
described
in
the
previous
chapters.
It
is
quite
powerful
enough
for use
with
a
trailer, side,
or
fore
car. With a
two-speed
gear,
it
may
also
be
used
for
a
tri-car.
This
is
not
an
experimental
engine,
but one
that has
been
made
and well
tried
over
some
thousands of
miles,
giving
every
satis-
faction.
It
is
of
original
design
and
simply
con-
structed
with
as few
parts
as
possible
(see
the
vertical
'section,
Fig.
34,
in
which
the
valve
springs
are
not
shown).
The
patterns
for all the
parts
are
finished,
and are
available
to
readers of
this
handbook
who would like
to
purchase
the
castings
instead
of
making
their
own
patterns,
so
that
an immediate
start
could
be
made.
The
cylinder
pattern
is
an
exceedingly
difficult one
for an amateur
to
make
;
in
fact,
it
is
the work of
a first-class
pattern-maker
to turn
out
a
good
working
pattern.
Fig.
35
is
a
section
of
the
cylinder
through
the
line
x x
in
Fig.
36,
which
is
a
plan
of
the
top.
Fig.
37
is
a
plan
of
the
bottom
or
open
end
of
the
cylinder.
Boring
Cylinder.
The
first and most im-
portant part
to
be taken
in
hand
is
the
cylinder.
The
boring
and
machining
of
this
calls
for
the
greatest
care
and
skill
to
obtain
really good
re-
sults.
The
cylinder,
etc.,
being
all
in
one cast-
ing,
increases the
difficulty
of
accurate
boring,
but
makes
a
much
more
satisfactory
job
when
finished.
Before
starting
the
boring operation,
the
casting
should
be
carefully
examined
for
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MOTOR
BICYCLE
BUILDING.
Fig.
34. Vertical
Section
of
3|-h.p.
Petrol
Engine.
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MAKING A
3A-H.P.
PETROL
MOTOR.
4
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50
MOTOR
BICYCLE BUILDING.
carefully
chipped
'off.
The
open
end should
be
filed
level,
and a
piece
of hardwood
fixed across
the
open
end.
From
a centre
marjked
on
this
hardwood
the
size
of bore can be
scribed off
and
lightly
centre-dotted.
The bore
is
82
mm.,
or
approximately
^
T
in. under 3
in.
;
and the
stroke
is
3^
in.
In
outlining
the
bore,
it
is
advisable
to mark
just
outside
the exact
bore,
so that the
boring
will
not
completely
obliterate
the
marks.
There
is a
small boss on the
top
of the
cylinder;
this boss is
perfectly
central
with
the
cylinder
walls,
and is
placed
there
to
assist
in
setting
the
casting
true
for
boring,
and
to take
the centre
for
turning
up
the outside below the
radiators.
The boss should be
carefully
centred,
and
drilled
up
with
a
small
hole,
and
countersunk
to
the
same
angle
as
the lathe centres. Another
use for this
boss
is
to time the
valves,
by
passing
a
wire
down
a
hole
drilled
right through
and afterwards
stopped
up
with
a
small screw.
The
casting
may
be
strapped
to the
face
plate,
and
bored
up
with a tool
in
the slide-rest
or
strapped
down
to
the
saddle
and
bored with
a
stiff
boring
bar held in a
firm,
solid
chuck.
By
the first
method, cylinders may
sometimes
be
bored
accurately,
but the
chances
are
against
it.
The
latter method
will
be more
satisfactory.
A
good
stiff
boring
bar,
not
less
than
li in.
in
diameter
and
no
longer
than
absolutely
neces-
sary,
should
be used.
This should be fitted
with
a
flat cutter
made
from
l|-in.
by
j-in.
steel,
double
cutting,
the corners
being
rounded
off
and
the
cutting edges slightly
backed off.
Three
cutters
are
required,
a
roughing,
second,
and
finishing,
the last
being
only
slightly
rounded
on the
corners
and
the
cutting
edges
finely
finished
off
on
the
oil-
stone to
the size of
the bore
that
is,
82 mm.
The
cutter must
run
dead
true
in
the
lathe,
or the
bore
will
be
greater
than
the
width
of
the
cutter.
Three cuts should
be
sufficient,
the
finish-
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MAKING A
3i-H.P. PETROL
MOTOR.
ol
ing
one
being
a mere
scrape.
During
the
finishing
cut
and
the one
before
it,
the
lathe
must
not
be
stopped
from
the
commencement
to
the
finish
of
the
cut.
The
job
may
be done
with one
cutter,
one
end
only
cutting,
and the cutter
adjusted
farther
out
for
each
cut;
but
it
should be
freshly
sharpened
for the
finishing
cut. A
single-ended
cutter
is
more liable
to
spring
and follow
in-
equalities
in the
casting
than
a
double-ended
one,
and
for
this
reason
at
least
one
extra
cut
should be
employed
in
the
operation.
The
casting
must
be
very carefully
set,
and
Fig.
37.
Plan
of
Bottom or
Open
End
of
Cylinder.
bolted
down with
good
broad
straps,
one
strap
coming
across the thick
part
of the
valve
cham-
ber and
the other
across
the
flange
at
the bottom.
Secured in this
manner the
casting
is less
liable
to
be
sprung
out
of
shape.
The
cylinder
walls
being
only
^\
in. thick
(finished),
no
allowance
can
be made for
any
inaccuracy
in
setting.
The
small
lug
on
top
of
the
cylinder
will
here be found
useful,
as the
back
centre
of
the
lathe can
be
brought
up
close
to
the
casting
and
used
to
test
the
accuracy
of
this end
;
the
open end,
of
course,
can
be
more
easily
set
by
the
cutter
edges.
The
cutter
slot
in
the
boring
bar
should
be
within
-4
in.
of
the
end,
to avoid
any
risk
of
the
end
of
the
bar
coming
in
contact
with
the
cylinder
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62
MOTOR BICYCLE BUILDING.
end
and thus
shifting
the
setting;
this
would be
disastrous
in
the
finishing
cut
or the
one before
it.
It will
be
noticed
that the last
f
in.
of
tne
cylinder
is
shown counter-bored.
It will
not
be
necessary
to
bore
this
part
if
the
casting
is
accurately
set,
as the
casting
is
cored
out at
this
part
y
1
^
in.
larger
than
the
finished bore.
Machining
Chamfer
at
Mouth
of Cylinder.
At
this
setting,
after
the
bore
is
finished,
the
chamfer
at
the
mouth
of
the
cylinder
should be
machined.
This can
be
done
with a
separate
cutter,
or a
corner of
the back
portion
of on-e used
for
boring
may
be filed
to
the
necessary
shape.
This
chamfer
is
necessary
for
the
easy
insertion
of
the
piston
when
the-
rings
are
in
position.
The
extreme
end
may
also
be
trued
up
with
the
cutter
at this
setting.
This
should be done to
allow
of
the
under
part
of
the
flange
being
-^
in.
from the
end
and
the
cylinder
6|
in.
deep.
To machine the
valve
chamber,
the
casting
should
be
firmly
bolted
down
to
a
perfectly
true
face
plate,
2|
in.
out
of
the
centre,
to
get
the
opening
true.
As
the
sur-
face
in
contact
with
the
face-
plate
is
so
small,
the
casting
is
liable
to
shift
during machining
unless
it
is
very
firmly
bolted
down.
A
sheet
of brown
paper
placed
between
the
face
plate
and the
mouth
of
the
casting
will
greatly
assist
in
keeping
it
from
shifting.
Valve
Seating,
Opening,
etc.
When
set
true,
bore
out
and
screw
the
exhaust-valve
guide
holes
A
(Fig.
35)
to
f-in.
whitworth. With
a hook
tool,
face the
under
side
of
this
hole
for
the collar
on
the
guide
to bed
true
against
;
this collar
will be
1
T
V
in.
in
diameter.
The
seating
for
the
exhaust
valve
will
be
bored
out
If
in.,
the
upper
side
being
chamfered
as
shown
and
the
top
trued
up.
The
opening
for
the inlet
valve
is
bored out
lj in.,
and
chamfered
the
same
as
the exhaust
opening
;
\
in.
above this
bore
out
If
in.
;
the
remaining portion
B
(|
in.)
is
bored
1
T
^
in.
bare,
and
screwed 20
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MAKING
A
3A-II.P.
PETROL
MOTOR. 53
threads
to
the
inch,
which will
make
it
If
in.
at the
bottom
of
the
thread.
Face
off
the
top
of
the
opening
true
to
the
dimensions
given.
Turning
up
Outside
of
Cylinder.
To
turn
up
the outside
of
the
cylinder
below the
radiators,
the
casting
should
be
run on
the
centres. For
this,
a
large
centre
to fit
the
back
poppet
of
the
lathe
must
be
made,
or
the
mouth
of
the
cylinder
may
be bridged
with
a
stout
piece
of
iron
or
steel
carefully
fitted to
the
bore
and
centred
true. The
outside between
the
lower
radiator
and
the
top
of
the
flange
is turned to
3
T
7
^in.,
the
flange
being
left
$
in.
thick,
and
the
shoulder
3j
in.
in
diameter
by
-j^
in.
deep
;
this
shoulder should be
left
with a
very
slight
taper
on
it,
so
that
it
may
fit
tight
into
the
opening
in the
top
of
the
crank
case.
Opening for
Exhaust
Pipe,
etc.
The
opening
for
the exhaust
pipe,
which
is
indicated
by
the
dotted
circle
c
(Fig.
1)
in
the
centre
of
the
valve
chamber,
must
now
be-
drilled
and
tapped.
This
is
lj
in.
by
26
threads,
and is best
done
on the
drilling
machine,
using
a
suitable
tap
to
form the
thread,
as
it
is rather
awkward
to chuck or
hold
in
the
lathe.
The
sparking-plug
hole
D
is drilled
and
tapped
|~J
in.
by
17
threads,
and is faced
on
the
outer
surface.
Flange
on
Cylinder
Bottom. The
flange
on
the
cylinder
bottom
is left the
full
size
at
present,
being
filed
off
flush
with
the flange
on
the
top
of
the
crank case after
the
two
parts
are
fitted
to-
gether.
Holes
for
Holding-down
Bolts.
The
four
f-in.
holes for
the
holding-down
bolts,
shown
in
the
plan
of
the
bottom
end at
Fig.
3,
should
be
drilled
in
such
a
position
as
to
Leave
an
equal
amount of
metal
round
the
corresponding
holes
in
the
crank
case,
but
keeping
the
holes
sufficiently
far from
the
outer
face of the
cylinder
to enable
the corners
of
the
bolt
heads
to clear
properly.
Piston. The
piston
casting
should now
be
-
8/10/2019 Motorbicycle building
56/166
54
MOTOR
BJCYCLE
BUILDING.
trimmed
up by
filing
or
carefully
chipping
off
all
rough projections
left
from
the
foundry.
The
cast-
ing
should be chucked
by
the
projection
left
on
the
end
of
the
casting,
in
a
3-jaw
or
4-jaw chuck,
and
should
not
be
shifted
until
all
the
turned
work
is
finished.
In
setting
the
casting,
true
up
from
the
inside,
for
unless the inside is
true the
piston
will
be
very
thin
on
one
side
when
finished,
as
the
walls
will
be
rather
light
in
parts.
Turn
up
the
outside
perfectly
parallel
from end
to
end,
82
mm.
in
diameter;
it should
be
a
fairly
easy
fit
in
the
cylinder
at this
stage.
Turn
as
near
the
size
as
possible
with
a
light
finishing
cut,
and
smooth off
to
the
final
fitting
with
a dead smooth file. True
up
the
open
end,
and
with
a
good
sharp
parting
tool
cut
down
the
head
to
the
projection by
which
the
casting
is
held,
leaving
it
3j
in.
long
from end
to
end.
Ring
Grooves in Piston.
The
ring
grooves
may
now
be
put
in
;
these
are
y^-
in.
wide
by |
in.
deep,
and
are
g
in.
apart,
the first or
top
one
starting
J
in.
from
the
end.
The
tool
with
which
these'
are cut
must
be
carefully
made
and
set,
so
as
to
leave the sides
perfectly square
and
the
corners
sharp.
A
tool
made as a
parting
tool,
jusb
yV
i
n
-
wide,
with
the sides
slightly
backed
off,
will
do
the
job
at
one
cut,
and ensure them
being
all the same width
;
but
unless
the
lathe
is
a
good
solid
tool,
free from
spring,
the
yV^
n
-
cu
^
may
be
too
much for
it
and
set
up
chattering.
In this
case,
a
narrower
tool
must
be
made,
not
more
than
g
in.
wide.
Whichever
way
the
job
is
done,
the sides of
the
grooves
must
be
perfectly
parallel
and
square.
A
small
sheet-metal
template
should
be
filed
out for
the
purpose
of
testing
them
for
depth
and
width.
Gudfjeon-pin
Hole. At a distance
of
lj
in.
from
the
top
end,
scribe a
line
round
the
piston
with
a
sharp-pointed
tool
held in
the
slide-rest